testthat (version 2.1.1)

output-expectations: Expectation: does code produce output/message/warning/error?

Description

Use expect_output(), expect_message() and expect_warning() to match specified outputs. Use expect_error() or expect_condition() to match individual errors or conditions. Use expect_silent() to assert that there should be no output of any type.

Usage

expect_output(object, regexp = NULL, ..., info = NULL, label = NULL,
  width = 80)
expect_error(object, regexp = NULL, class = NULL, ..., info = NULL,
  label = NULL)
expect_condition(object, regexp = NULL, class = NULL, ...,
  info = NULL, label = NULL)
expect_message(object, regexp = NULL, ..., all = FALSE, info = NULL,
  label = NULL)
expect_warning(object, regexp = NULL, ..., all = FALSE, info = NULL,
  label = NULL)
expect_silent(object)

Arguments

object

Object to test.

Supports limited unquoting to make it easier to generate readable failures within a function or for loop. See quasi_label for more details.

regexp

regular expression to test against.

If NULL, the default, asserts that there should be an output, a messsage, a warning, or an error, but does not test for specific value.

If NA, asserts that there should be no output, messages, warnings, or errors.

...

Arguments passed on to expect_match

all

Should all elements of actual value match regexp (TRUE), or does only one need to match (FALSE)

perl

logical. Should Perl-compatible regexps be used?

fixed

logical. If TRUE, pattern is a string to be matched as is. Overrides all conflicting arguments.

info

Extra information to be included in the message. This argument is soft-deprecated and should not be used in new code. Instead see alternatives in quasi_label.

label

Used to customise failure messages. For expert use only.

width

Number of characters per line of output. This does not inherit from getOption("width") so that tests always use the same output width, minimising spurious differences.

class

Instead of supplying a regular expression, you can also supply a class name. This is useful for "classed" conditions.

all

For messages and warnings, do all need to match the regexp (TRUE), or does only one need to match (FALSE)

Value

The first argument, invisibly. If expect_error() captures an error, that is returned instead of the value.

Details

Note that warnings are captured by a custom signal handler: this means that options(warn) has no effect.

See Also

Other expectations: comparison-expectations, equality-expectations, expect_length, expect_match, expect_named, expect_null, inheritance-expectations, logical-expectations

Examples

# NOT RUN {
# Output --------------------------------------------------------------------
str(mtcars)
expect_output(str(mtcars), "32 obs")
expect_output(str(mtcars), "11 variables")

# You can use the arguments of grepl to control the matching
expect_output(str(mtcars), "11 VARIABLES", ignore.case = TRUE)
expect_output(str(mtcars), "$ mpg", fixed = TRUE)

# Messages ------------------------------------------------------------------

f <- function(x) {
  if (x < 0) message("*x* is already negative")
  -x
}
expect_message(f(-1))
expect_message(f(-1), "already negative")
expect_message(f(1), NA)

# You can use the arguments of grepl to control the matching
expect_message(f(-1), "*x*", fixed = TRUE)
expect_message(f(-1), "NEGATIVE", ignore.case = TRUE)

# Warnings --------------------------------------------------------------------
f <- function(x) {
  if (x < 0) warning("*x* is already negative")
  -x
}
expect_warning(f(-1))
expect_warning(f(-1), "already negative")
expect_warning(f(1), NA)

# You can use the arguments of grepl to control the matching
expect_warning(f(-1), "*x*", fixed = TRUE)
expect_warning(f(-1), "NEGATIVE", ignore.case = TRUE)

# Errors --------------------------------------------------------------------
f <- function() stop("My error!")
expect_error(f())
expect_error(f(), "My error!")

# You can use the arguments of grepl to control the matching
expect_error(f(), "my error!", ignore.case = TRUE)

# Silent --------------------------------------------------------------------
expect_silent("123")

f <- function() {
  message("Hi!")
  warning("Hey!!")
  print("OY!!!")
}
# }
# NOT RUN {
expect_silent(f())
# }